Modern footwear is available in a myriad of materials and fabrications. Despite great advances in support, there has been relatively little development in thermal management of footwear. The foot generates heat while walking, running, or even at rest. As heat is generated by the foot, the shoe temperature begins to rise, and the foot begins to perspire. Excessive perspiration around the foot leads to foot and shoe odor among other problems.
Specifically, the heat and perspiration released by the foot causes several problems. A wet and warm shoe interior is uncomfortable for the user to wear. Further, the perspiration released by the foot contains sodium chloride and urea, which can stain or discolor the outer surface of the shoe, degrading the expressive value of the shoe to the wearer. Moreover, the perspiration and heat around the foot creates an ideal environment for fungi and bacteria to thrive. Fungi and bacteria consume dead skin cells, and produce waste that is the source of foot odor. Fungi and bacteria convert the amino acid methionine to methanethiol which has a sulfuric smell. As physical activity increases, foot perspiration, bacterial growth, and bacterial waste production all increase, causing odor to intensify. Finally, a warm and moist shoe provides an ideal environment for foot disease, such as Athlete's foot, to thrive.
One approach minimizing the problems stated above is to provide shoe ventilation to transfer heat and moisture away from the foot. The theory behind shoe ventilation is to reduce the interior temperature and humidity of the shoe by transferring heat and foot perspiration generated by the foot away from the interior of the shoe. Since perspiration decreases with decreasing temperature, a decrease in the interior temperature of the shoe decreases the rate of perspiration around the foot. Thus, the goal of shoe ventilation is to maintain an interior shoe temperature as close to the ambient air temperature as possible. By forcing ambient air around the foot and into the shoe cavity, heat and moisture generated by the foot is transferred away from the foot by the circulating air.
Systems have been proposed in the prior art for ventilating the area under the foot. These systems have been directed at systems in the sole of the shoe actuated by foot movement during walking or running to circulate air within the interior of the shoe. While these systems help transfer excess heat away from the bottom of the foot surface they are ineffective because they do not transfer heat away from the top, rear, and sides of the foot. This allows excessive heat and moisture to build up inside the shoe. It is possible to make a shoe upper out of mesh or another relatively breathable material, however, these constructions are only suitable for certain types of running shoes or water shoes, and are not appropriate for street shoe constructions or office wear.